The Home Inspection and Ledger Flashing

Diagram of ledger flashing installed. Extending from behind siding over top of the ledger board.

What is Deck Ledger Flashing?

Most realtors and home buyers are not sure what deck ledger flashing is or its purpose and why it keeps coming up in home inspection reports. What I am writing, is not meant to be an expert treatise on deck ledger flashing and all of it possible installation methods and damaging results. My purpose is to give a general understanding of what deck ledger flashing is and some of the results of its absence. Please forgive my lack of skill with word press in laying out the pictures and text.

During a home inspection of a deck, one of the critical items we look for is ledger flashing. Unfortunately, deck ledger flashing was not used on most of the decks I have seen until after 2005 or so. Some homeowners and builders have found creative ways to retrofit and improvise to protect the home structure in the absence of deck ledger flashing.

I will be using pictures to show where ledger flashing should be placed, what it looks like during and after installation, how to see whether it is present or not, and some of the damaging results that can occur if it is absent.

Where is deck ledger flashing installed?

In the picture below, the arrows point to the spot where the ledger flashing would go. The main point to take away is the junction of the ledger board and house plywood sheathing. When ledger flashing is absent, rainwater can get behind the ledger board and damage the sheathing. In some cases over time, water will destroy the sheathing and finally have access to the rim joist and framing of the home, causing damage.

2nd Floor Rim Joist. The ledger board for the deck would be attached at the rim joist after exterior wall sheathing was installed.

Deck framing prior to installation of ledger flashing.

Purpose and Installation of Deck Ledger Flashing.

Ledger flashing extending behind the siding and across the junction of the deck ledger board and wall sheathing.

Retrofitting ledger flashing to an older deck. Deck boards are not yet installed.

In these following pictures, you will see how deck ledger flashing is installed to prevent water from accessing the structure. In the picture to the far right, the ledger flashing is in the process of being installed. The flashing covers the junction of the deck ledger board and the exterior wall surface, preventing water from getting behind the ledger board and directing the water away from the structure.

The picture to the right shows ledger flashing being retrofitted to a preexisting deck with stucco siding. Here the top edge of the flashing will have to be sealed to the stucco face unless the stucco is removed or counter flashing installed. Again the main point is to see how the flashing prevents water from getting behind the ledger board and is directed to the exposed surface of the ledger board or beyond.

This diagram shows an exterior wall breakdown. Siding, ledger board, and flashing are visible, to help see their placement.

The diagram shows the location of the ledger flashing and the ledger board.

Deck Ledger Flashing Is Visible from Below Deck.

Here the pictures show a view of ledger flashing from underneath the deck. This can be a simple way to check for the presence of deck ledger flashing. The lip on the one installation is larger than normally found.

Deck ledger flashing visible from below.

Typical view of ledger flashing from below.

Deck ledger flashing visible from below deck.

Signs of damage from the Lack of Deck Ledger Flashing.

During a home inspection, these pictures were taken showing the lack of deck ledger flashing. Without the presence of deck ledger flashing, water has made its way behind the deck ledger board and is affecting not just the wall sheathing but the stucco finish also.

Water getting behind the deck ledger board, is coming through the stucco finish.

The lack of ledger flashing is allowing water to affect the stucco and the wall sheathing behind it.

Unfortunately, in these pictures, the exterior wall sheathing has broken down and significant damage to the rim joist of the home has occurred. At this stage, structural issues are involved. A licensed framing contractor will need to evaluate how repairs can be made. Another issue to consider is the wet framing draws the attention of termites.

Water has made its way past the wall sheathing and is damaging the rim joist of home.

As a result of high moisture levels, wood destroying insects has also added to the damage at rim joist.

As a result of high moisture levels, wood destroying insects has also added to the damage at rim joist.

A Licensed Contractor Can Give You Options.

The importance of the deck ledger board flashing is obvious. In homes built prior the when the building code required it’s installation, there are options available. If your home inspection reveals the lack of ledger flashing or the home you own lacks ledger flashing, a licensed contractor can present you with options.